., president obama addressed the nation from the white house press briefing room. >> any responsible individuals, any responsible groups, will feel the full weight of justice. >> for more on the conditions of the victims, nbc's ron allen is at mass general hospital, where many of the injured are being treated. what can you tell us about the range of injuries? >> the range of injuries is serious. there were about 30 people taken to hospitals yesterday, that were in serious, grave condition. here at mass general, they told us there are at least eight people who are in surgery and may have multiple surgeries in the days to come. as the doctor said in the sound clip that you aired, most of the injuries are lower extremities, damage to bones, tissue, a lot of damage from flying shrapnel. there were amputations that happened or partial amputations. some are in critical condition at some of the hospitals. there is the possibility that the death toll could increase. the bottom line is, this is going to be a situation that's going to go on for some time. one other point. the doctors said they